Methods for supplying fibrous insulating materials by injection under air pressure provide a generally economical method of insulating a desired space. Such methods are economical at least partly because relatively inexpensive fibrous materials such as cellulose, or mineral fibers, fiberglass and the like can be used, as described, for example, in U.S. Pat. No. 4,487,365 issued Dec. 11, 1984, to Sperber and U.S. Pat. No. 4,530,468 issued July 23, 1985, to Sperber, and also because of the relative speed with which the insulation can be blown in compared with the installation of batt-type insulation.
The process of blowing-in fibrous insulation, however, typically produces insulation with nonhomogeneous density. This is partly because the first portions of blown-in insulation are compacted when they are impacted by later portions of blown-in insulation. Insulation in the lower regions of a vertical column of insulation are compacted by the weight of the insulation above. Furthermore, there is a settling of the fibers over time reducing the homogeneity of the insulation product. Although an adhesive can be used to assist in maintaining the loft of fibrous insulation, as described in the Sperber patents above, the adhesive may have insufficient time to set, cure or dry before impaction from succeeding portions of insulation occurs and may have insufficient strength to withstand the force of impact from succeeding portions of blown-in insulation. Additionally, the adhesive by itself may not be sufficiently spread or mixed with the fibers to provide the desired separation of the fibers.
In general, compacted or densified fibrous insulation has a lower insulating capacity compared to less dense or un-compacted fibrous insulation. Thus, if, for example, a vertical wall is to be insulated at a given R-value, the upper, typically non-compacted region must be insulated at a greater-than-desired R-value in order to assure that the lower, typically compacted regions attain at least the desired R-value. In this way, compaction commonly accompanying blown-in insulation increases insulation costs.
As opposed to fibrous insulation, insulation comprising a solid "foam" is used in some applications. Although fibrous material can be incorporated into such foam as crystallization sites, fillers, reinforcements and/or opacifiers, as described in U.S. Pat. No. 4,402,892 issued Sept. 6, 1983, to Helser, it is the solid foam itself, rather than the fibers, which produces the insulation effect. In order for such insulation to fill a void, it is first produced in a fluent form and then cured or dried to form the solid foam. Thus, the fluent foam must be capable of substantial solidification into a permanent body. Materials which are capable of this solidification such as a cementitious material, as described in the Helser patent, or resin materials as described in U.S. Pat. No. 4,103,876 issued Aug. 1, 1978, to Hasselman, Jr. et al. and U.S. Pat. No. 4,135,882 issued Jan. 23, 1979, to Harkness et al. are typically more expensive than fibrous insulation materials. Furthermore, many foamed insulation materials require relatively expensive and time-consuming additional steps to accomplish curing or drying, such as a heating step.
U.S. Pat. No. 4,447,560 issued May 8, 1984, to Piersol describes forming a fibrous sheet by agitating a mixture of a foamable solution and a slurry of binder-coated insulation fibers to homogeneously suspend the fibrous slurry. In contrast, the present invention does not utilize a slurry of fiber and binder materials but requires the use of pressurized air to provide spreading of insulation fibers to achieve a desired degree of fiber "fluffiness." Additionally, the foam material desired herein is already in its agitated state when it is mixed with the fibers. Furthermore, the insulation mixture of the present invention is directly blown into a formed cavity at a building construction site; there is no formation of a batt-type insulation or a standard sheet of fibrous material. There is also no step of heating for drying purposes after the insulation material is located in the cavity.